3d Printing Theory

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CHAPTER 3
UPDATED BACKGROUND THEORY
3.1 Relevant Literature Search For GP2
3.1.1 What is 3D printing
3D printing is defined as “The action or process of making a physical object from a three-dimensional digital model, typically by laying down many thin layers of a material in succession . ” 3D printing can refer to a number of different processes that use different technologies such as stereo-lithography or metal sintering or melting.
3.1.2 How it works
Since 3D printing works by adding layers on top of another, CAD (Computer Aided Design) files must be broken into layers and these layers must be translated into motion commands that are sent to the 3D printer. 3D printing can be done using many different materials such as PLA (Polylactic
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One of the limitations of 3D printing is that there is no single method that can be used for all materials and all technologies. For example some 3D printers process materials like nylon, plastic, ceramic and metals in the form of powder using a heat source, like a laser, to melt or fuse the powder particles together into the required shape and form. Other printers have technologies that process polymer resin materials and again utilize a laser to solidify the resin in ultra thin layers that form the required 3D object.
3.1.3 Extrusion/ Fused Deposition Modeling (FDM)/ Freeform Fabrication (FFF)
Fused deposition modeling is the most widely used 3D printing process. It utilizes the extrusion of thermoplastic material. This process works by melting a thermoplastic filament that is then deposited, using a heated extruder/nozzle, one layer at a time, onto a build platform. The material is deposited according to the 3D data supplied to the printer via software. Each layer hardens as it is deposited and bonds to the previous layer.
Usually this type of printing requires support structures for any models with overhanging geometries. water-soluble material can be used for this purpose , which allows support structures to be washed away once the print job is complete. Breakaway support materials are also used; they can be removed by manually snapping them off the printed
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• Supports required on some materials / geometries.
• Support design / integration / removal is difficult.
• Weak Z-axis.
• Slow on large / dense parts
• Weak layer-to-layer adhesion
3.1.4 Stepper motors
3.1.4.1 What is a stepper motor:
A stepper motor is an electromechanical device, which converts electrical pulses into mechanical movements. The shaft of a stepper motor rotates in step increments when electrical command pulses are applied to it in the proper sequence. The sequence of the applied pulses is directly related to the direction of motor shafts rotation. The speed of the motor shafts rotation is directly related to the frequency of the input pulses and the length of rotation is directly related to the number of input pulses applied.

3.1.4.2 Advantages:
• Rotation angle of the motor is proportional to the input pulse.
• Motor has full torque at standstill
• Precise positioning and repeatability of movement (accuracy of 3 – 5% of a step and this error is non cumulative from one step to the next)
• Excellent response to starting/stopping/reversing
• Reliable since there are no contact brushes in the motor (dependant on life of bearing instead of

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